Charlie,
Mine was a new installation so I needed something. I ended up bailing out on the Allen-Bradley idea. At the time, Allen-Bradley's Ethernet I/O wasn't developed enough or even available.
So Field Point was one of the solutions I could find for Ethernet I/O. I used Wonderware HMI software and it's OPC Link I/O driver to talk with the OPC enabled Field Point I/O. This would not work with Allen-Bradley and still won't as far as I know. I never went back to try it, but typically A-B only communicates with "partner" integrators.
The Wonderware scripting language took the place of the PLC and its logic program. Not the best solution, but it worked.
Jim